Iodide action mechanisms

At present the mode of action of various inorganic ions and of the pituitary hormone, thyrotropin, on iodide concentration by the thyroid cannot be explained, and it is likely that it will remain unexplained so long as the iodide-concentrating mechanism itself is unsolved. 

Other Radioprotective Chemicals. The bis-methylthio- and methylthioamino-derivatives of 1-methylquinolinium iodide and l-methylpyridinium-2-dithioacetic acid provide reasonable protection to mice at much lower doses than the aminothiols, which suggests a different mechanism of action (139). One of these compounds, the 2-(methylthio)-2-piperidino derivative of the l-methyl-2-vinyl quinolinium iodide (VQ), interacts with supercoUed plasmic DNA primarily by intercalation. Minor substitutions on the aromatic quinolinium ring system markedly influence this interaction. Like WR-1065, VQ is positively charged at physiological pH, and the DNA-binding affinities of VQ and WR-1065 appear to be similar. 

The use of iodotrimethylsilane for this purpose provides an effective alternative to known methods. Thus the reaction of primary and secondary methyl ethers with iodotrimethylsilane in chloroform or acetonitrile at 25—60° for 2—64 hours affords the corresponding trimethylsilyl ethers in high yield. The alcohols may be liberated from the trimethylsilyl ethers by methanolysis. The mechanism of the ether cleavage is presumed to involve initial formation of a trimethylsilyl oxonium ion which is converted to the silyl ether by nucleophilic attack of iodide at the methyl group. tert-Butyl, trityl, and benzyl ethers of primary and secondary alcohols are rapidly converted to trimethylsilyl ethers by the action of iodotrimethylsilane, probably via heterolysis of silyl oxonium ion intermediates. The cleavage of aryl methyl ethers to aryl trimethylsilyl ethers may also be effected more slowly by reaction with iodotrimethylsilane at 25—50° in chloroform or sulfolane for 12-125 hours, with iodotrimethylsilane at 100—110° in the absence of solvent, " and with iodotrimethylsilane generated in situ from iodine and trimcthylphenylsilane at 100°. ... 

Flow cytometry (FCM) is widely used for exploring mechanism of action of compounds that compromise proliferation since it is rapid, accurate and usable for any cellular context [5], In this chapter we want to point out technical and strategic aspects of use of FCM for cell cycle studies of a putative anticancer agent. As an example we used Edotecarin, a topi inhibitor, firstly evaluating proliferation outcome and classical DNA content analysis by propidium iodide, and then since the compound treatment produced cell cycle perturbation difficult to interprete, a two-parametric analysis by 5-bromo-deoxyuridine (BrdU) was applied for separating cell cycle phases. Moreover we put our efforts into identifing specific cell cycle arrest not easily demonstrable by previously described methods, through the use of in vitro kinetics ( pulse and chase ). Finally, in vivo assessment of efficacy and biomarkers modulation after treatment was analyzed. 

What is the basic mechanism of action of thiocyanate in inhibiting iodide uptake by the thyroid gland ... 

Thyroid injury after chronic skin application of resorcinol has been reported several times. In 1977, Katin and colleagues published a case of hypothyroidism following regular application of a 2% resorcinol cream in a chronic dialysis patient suffering from pruritus. The mechanism of action seems to be as follows the presence of a hydroxy group in the meta position in the resorcinol would block the metabolism of iodine by inhibiting the peroxidase needed to oxidize iodide into iodine, the only form that can be assimilated by the body. 

Homolytic cycUzation of a bromo-alkene yields dthydropyrroles but bromo-alkynes by the same mechanism form a mixture of pyrrole and 3-methyIene-pyrrole in high yield (the ratio is not stated) [3434]. Aryl radicals produced by the action of samarium di-iodide on an aryl Iwomide react with an o-propynyl-amino (or propynyloxy—see Section 1.3) side-chain to form a new fus pyrrole (or furan) under mild conditions. The corresponding allylamino bromides give... 

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